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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 940 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 4.8
  2. 2.Best estimate of 2488 ÷ 38? (a) 620 (b) 6200 (c) 62
  3. 3.Best estimate of 1737 ÷ 46? (a) 350 (b) 3500 (c) 35
  4. 4.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  5. 5.Best estimate of 5111 ÷ 76? (a) 640 (b) 64 (c) 6400
  6. 6.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.4
  7. 7.√32 to 1 decimal place? (a) 5.4 (b) 5.7 (c) 5.5 (d) 5.6
  8. 8.Best estimate of 1554 ÷ 24? (a) 78 (b) 7800 (c) 780
  9. 9.Best estimate of 1908 ÷ 27? (a) 6400 (b) 640 (c) 64
  10. 10.√61 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.8
  11. 11.Best estimate of 2044 ÷ 83? (a) 2600 (b) 26 (c) 260
  12. 12.Best estimate of 4782 ÷ 62? (a) 800 (b) 8000 (c) 80
  13. 13.√85 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.5 (d) 9.4
  14. 14.Best estimate of 2484 ÷ 82? (a) 31 (b) 310 (c) 3100
  15. 15.√88 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  16. 16.√92 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  17. 17.Best estimate of 2450 ÷ 27? (a) 8200 (b) 82 (c) 820
  18. 18.Best estimate of 1622 ÷ 56? (a) 27 (b) 2700 (c) 270
  19. 19.Best estimate of 2366 ÷ 37? (a) 590 (b) 59 (c) 5900
  20. 20.√38 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 6.3
  21. 21.Best estimate of 934 ÷ 44? (a) 23 (b) 230 (c) 2300
  22. 22.√89 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.1 (d) 9.3
  23. 23.Best estimate of 3764 ÷ 58? (a) 630 (b) 63 (c) 6300
  24. 24.Best estimate of 1550 ÷ 26? (a) 520 (b) 5200 (c) 52
  25. 25.Best estimate of 7093 ÷ 81? (a) 8900 (b) 89 (c) 890
  26. 26.Best estimate of 1012 ÷ 56? (a) 170 (b) 1700 (c) 17
  27. 27.Best estimate of 5749 ÷ 84? (a) 720 (b) 7200 (c) 72
  28. 28.√35 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 5.8
  29. 29.Best estimate of 1365 ÷ 36? (a) 3400 (b) 340 (c) 34
  30. 30.√79 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  31. 31.Best estimate of 816 ÷ 57? (a) 14 (b) 1400 (c) 140
  32. 32.√45 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7
  33. 33.√98 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.8 (d) 9.6
  34. 34.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.9
  35. 35.Best estimate of 1716 ÷ 26? (a) 5700 (b) 57 (c) 570
  36. 36.Best estimate of 4964 ÷ 76? (a) 620 (b) 6200 (c) 62
  37. 37.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.2
  38. 38.Best estimate of 683 ÷ 31? (a) 230 (b) 23 (c) 2300
  39. 39.Best estimate of 1271 ÷ 39? (a) 3200 (b) 320 (c) 32
  40. 40.Best estimate of 7350 ÷ 79? (a) 920 (b) 9200 (c) 92

Answer key

  1. 5.1
  2. 62
  3. 35
  4. 9.3
  5. 64
  6. 6.1
  7. 5.7
  8. 78
  9. 64
  10. 7.8
  11. 26
  12. 80
  13. 9.2
  14. 31
  15. 9.4
  16. 9.6
  17. 82
  18. 27
  19. 59
  20. 6.2
  21. 23
  22. 9.4
  23. 63
  24. 52
  25. 89
  26. 17
  27. 72
  28. 5.9
  29. 34
  30. 8.9
  31. 14
  32. 6.7
  33. 9.9
  34. 8.6
  35. 57
  36. 62
  37. 6.3
  38. 23
  39. 32
  40. 92

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